In recent years, electronic parts such as plasma display panels (PDPs) and integrated circuit (IC) chips generate more heat along with their increasing performance. This has led to the necessity of taking measures to prevent function failure due to temperature rises in the electronic parts of electronic devices.
General measures to prevent function failure due to temperature rise involve attaching a heat radiator such as a metallic heat sink, radiation plate or radiation fin to a heat source such as an electronic part to facilitate heat dissipation. When a heat radiator is used, the heat radiator and the heat source are closely attached to each other via a sheet member having high heat conductivity (heat conductive sheet) in order to efficiently transfer heat from the heat source to the heat radiator.
Hence, heat conductive sheets sandwiched between a heat source and a heat radiator during use are required to have high heat conductivity.
To that end, for example, PTL 1 proposes a high heat conductive sheet formed by the steps of: shaping a composition containing a fluororesin that is solid at ordinary temperature, a fluororesin that is liquid at ordinary temperature and expanded graphite into a sheet by pressure application to provide a pre-heat conductive sheet; obtaining a laminate either by laminating a plurality of such preheat conductive sheets in the thickness direction or by folding or rolling such a pre-heat conductive sheet; and slicing the laminate at an angle of 45° or less relative to the lamination direction to provide a heat conductive sheet. The heat conductive sheet disclosed in PTL 1 includes strips containing fluroresins and expanded graphite (slices of the pre-heat conductive sheet(s) that constituted the laminate) joined together in parallel, with each strip containing a fluororesin that is solid at ordinary temperature, a fluororesin that is liquid at ordinary temperature, and expanded graphite. With such a configuration, the heat conductive sheet adheres well to a heat source and a heat radiator and hence can exhibit high heat conductivity.